linux-kernel - Re: [PATCH v1 2/5] lib/test_cpumask: fix cpu_possible

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Date:   Wed, 10 Aug 2022 12:06:38 +0800
From:   David Gow <davidgow@...gle.com>
To:     Sander Vanheule <sander@...nheule.net>
Cc:     Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Maíra Canal <mairacanal@...eup.net>
Subject: Re: [PATCH v1 2/5] lib/test_cpumask: fix cpu_possible_mask last test

On Wed, Aug 10, 2022 at 2:09 AM Sander Vanheule <sander@...nheule.net> wrote:
>
> Since cpumask_first() on the cpu_possible_mask must return at most
> nr_cpu_ids - 1 for a valid result, cpumask_last() cannot return anything
> larger than this value.  As test_cpumask_weight() also verifies that the
> total weight of cpu_possible_mask must equal nr_cpu_ids, the last bit
> set in this mask must be at nr_cpu_ids - 1.
>
> Fixes: c41e8866c28c ("lib/test: introduce cpumask KUnit test suite")
> Link: https://lore.kernel.org/lkml/346cb279-8e75-24b0-7d12-9803f2b41c73@riseup.net/
> Reported-by: Maíra Canal <mairacanal@...eup.net>
> Signed-off-by: Sander Vanheule <sander@...nheule.net>
> Cc: David Gow <davidgow@...gle.com>
> ---

Much better, thanks.

Reviewed-by: David Gow <davidgow@...gle.com>

Cheers,
-- David


>  lib/test_cpumask.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/test_cpumask.c b/lib/test_cpumask.c
> index 4ebf9f5805f3..4d353614d853 100644
> --- a/lib/test_cpumask.c
> +++ b/lib/test_cpumask.c
> @@ -73,7 +73,7 @@ static void test_cpumask_first(struct kunit *test)
>  static void test_cpumask_last(struct kunit *test)
>  {
>         KUNIT_EXPECT_LE(test, nr_cpumask_bits, cpumask_last(&mask_empty));
> -       KUNIT_EXPECT_EQ(test, nr_cpumask_bits - 1, cpumask_last(cpu_possible_mask));
> +       KUNIT_EXPECT_EQ(test, nr_cpu_ids - 1, cpumask_last(cpu_possible_mask));
>  }
>
>  static void test_cpumask_next(struct kunit *test)
> --
> 2.37.1
>